Dumped, lost, or abandoned fishing gear is the biggest plastic polluter in the earth's oceans, and a new Greenpeace report says it is deadly to marine life.

The report was compiled from the latest data on so called "ghost gear" polluting the earth's waterways.  Humans manage to dump more than 640,000 tons of ghost gear in the sea every year, the weight being equivalent to 55,000 double decker buses, or 16 Sydney Towers.  The environmental campaigner says the vast majority of it comes from illegal, unregulated and unreported fishing.

Greenpeace says this fishing gear spreads through the Earth's oceans via tides and currents.  There's so much of it that this discarded fishing gear is appearing on Arctic coastlines, washing up on remote Pacific islands, entangled on coral reefs, and littering the deep seafloor.

"The world's governments must take action to protect our global oceans, and hold the under-regulated fishing industry to account for its dangerous waste," said Louisa Casson, oceans campaigner at Greenpeace UK.  "This should start with a strong global ocean treaty being agreed at the United Nations next year."